Electric switch



Aug. 13, 1929, J. D. HlLLlARD ELECTRIC swn'cn 2 Sheets-Sheet Filed May 21, 1926 lll InvenTQr. John D.HH-icu`d, )3H

wf/ H15 Afornefg.

Aug. 13, 1929- J. D. HILLIARD 1,724,838

ELEGTRIQ swITcH Filed Mayv 21, 192e z sheets-sheet 2' InVe-wor John D. HH Hard, 5H f- Y HisvTTorne'H.

Patelaed Aug'. 13.11929.

UNITED STATES PATENT OFFICE.

y JOHN D. HILLIARD, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, .A CORPORATION `OF NEW YORK.

ELECTRIC SWITCH.

My invention relates to electric switches of the fiuid break type having explosion chambers associated with the contacts. In a common construction of such switches, the

explosion chamber has an opening in one end through which the movable contact rod iS withdrawn when the circuit is interrupted and in this opening an insulating bushing is fixed providing the necessary clearance l0 for the contact rod. The explosion chamber is surrounded by a shield of insulating material and a common manner of supporting the shield has been to secure it to a projecting portion of the bushing. In certain instances where the switch has been required to open a circuit under an excessive load, the bushing has been found.I to be fractured. The fracture has presumably been caused by stress transmitted to it by the insulating shield, the stress originating in the blast of gas and oil from the explosion chamber. It v1s an object of myinvention to provide an improved switch construction wherein the bushing shall be free from stress thus trans- Amitted to it and fracture and resulting breakdown of the bushing from this cause be avoided. i

'My invention will be better understood from the following description taken in conneetion with the accompanying drawing, and its scope will be pointed out in the appended claims.

Referring to the drawing, Fig. 1 is a crosssectional view of one embodiment of my invention and Figs. 2, '3 and 4 are similar views showing modified forms.

In the drawing the tank 1 containing insulating liquid 2 has projecting into/it the insulator bushing 3 by which the fixed contact 4 of the switch is supported. The fixed contact 4 is adjustably mounted on the end of the bushing' 3 by means of the adapter 5, further adjustment of the fixed contact being provided for by mounting it inv a holder 6 which is screw-threaded'into the lower portion of the adapter. This lower portion of the adapter is in the form of a plate 7 which constitutes the top or coverof the explosion chamber. The side walls and bottom of this member are shown in the form of a pot 8 preferably constructed of steel togive .it the necessary strength It has a relatively large opening in the bottom and in this opening is the bushing or throat member 10 of insulating material, the bush- -In Fig. 1 of the drawing I have shown it 1926. Serial N0. 110,758.

ing being clamped to the bottom of the pot by suitable means such as the nuts l1 and 12. The pot 8 is shown having the customary lining 18 and 14 of insulating material. The bushing 10 has the conical-shaped throat 1G for receiving the movable contact rod 17, the smallest portion of the throat being sufficiently larger than the rod 17 to provide for the necessary relief of pressure in the explosion chamber while the rod is being withdrawn. Surrounding the explosion chamber is the shield or cylinder 2U of insulating material which heretofore has been supported by a connection with the bushing 10. In accordance with my improved construction I support the shield 20 independently ofthe bushing 10 and preferably arrange the lower portion thereof with respect to the bushing whereby any stresses produced in the shield by the blast of gas and liquid Will noty be transmitted to the bushing.

A variety of different means may be employed to support the shield in this manner.

suspended from the upper portion of the explosion chamber. A ring 22 of insulation which rests on an external shoulder formed by the flange 23 of the potl 8 has the shield 20 secured to it by removable pins 2l. The lower portion of the shield is shown spaced from the pot by Wood spacers 25 to prevent lateral movement and as having a bottom comprisingthe ring 26 of insulating material pinned thereto, the opening in which is slightly larger than the exterior of the adjacent nut 11. Between and lapping over the nut 11 and the ring 26 is the ring 27 also of' insulating material. A complete covering of insulating material is thereby provided for `the `explosion chamber Without danger of stresses thereof being transmitted to the bushing at the bottom of the chamber.

In the modified form illustrated in F ig. 2

the insulation shield is supported at a point 100 opposite the top of the explosion chamber and also at the bottom. The shield 2O in this case is shown comprising closely fitting inner and outer cylinders, the inner cylinder being in two axially spaced portions separated by a metal ring 30. In screw-threaded engagement with this ring 30 is the supporting ring 31 which rests upon the plate 7 forming the top vof the explosion chamber and to which it is secured by the bolts 32. The lower portion of the shield 20'is separated from the -pot 8 by spacing blocks 33. The shield is partly supported by the insulation ring 34 which has an offset inner peripheral portion engaged by the supporting nut 35. Thisnut is shown threaded on the integral iange 36 on the bottom of the pot 8 although this ange may if desired be in the form of a separate nipple attached to the bottom of pot 8. Within the pot is the insulation lining 37 and 38 and clamped against the lining 38 is l-the throat bushing 39 corresponding to bushing 10 of Fig. 1. Clamping nuts 40 and 41 threaded on the bushing secure it to the pot 8 and between nuts 40 and 35 is the insulationtions shown Vin solid black .to the pot 8.

Spacing blocks 47 are used as before between the pot and the shield. The pot has insulation lining 37 and 38 and between the throat bushing 39 and the ring 46 is the flanged insulation ring 48 which also overlaps the nut Y 35. Nutsl40 and 41 serve to clamp the bushing to the pot. Y

In Fig. 4 I have shown a straight side pot 50 having threadedl connectionwith the topf plate 7. The insulation shield 20 in this case is not spaced from the side of the pot and is supported by the ring 34 and nut 35 as in Fig. 2. y.The explosion chamber is also provided wlth insulation lining 37 and 38, the

throat bushing 39, clamping nuts 40 and 41 and the insulation plate 42 all substantially the same as shown in Fig. 2.

What I claim as new and desire to secure by Letters Patent of the United States, is,-

1. A iuid break switch comprising a tank containing.y insulating liquid, an explosion chamber supported therein and having a fixed contact arranged at the top thereof and an insulating throat member in the bottom thereof, means for clamping said throatmember to said chamber, a movable contact adapted to be withdrawn through the throat member, a downwardly removable insulating shield surrounding said explosion chamber and means independent of the clamping means of the throat member for supporting the shield from the bottom of the explosion chamber whereby lateral stresses will not be communicated to the throat member from the shield.

2. A fluid break switch comprising an insulator bushing, an explosion chamber unit secured thereto comprising an adapter and an explosion chamber carried thereby, said chamber having a xed contact at one end thereof and a reduced portion having an opening for a Contact rod at the other end thereof, a throat bushing secured in said opening, an insulating shield for said cham# bor and adapter and means secured t6 the reduced portion of said chamber for supporting said shield independent of and out of Communication with said throat bushing.

3. A fluid break switch comprising a tank containing insulating liquid an insulator bushing projecting into the liquid, an adapter securedpthereto, an explosion chamber pot and a fixed contact secured. to the adapter, said pot having a throat clamped at one end thereof adapted to receive a movable Contact, an insulating shield for said adapter and pot and separate means for detachably clamping the shield to the pot adjacent the throat bushing and independently thereof, whereby lateral movement of the shield is not communicated to the bushing. v

. Inwitnessl whereof, I have hereunto set my hand this 20th day of May, 1926.

J OHN D. HILLIARD.

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